| There occurred two major geological events since the Mesozoic in Tuolai river of Qilian mountain, once occurred in the Mesozoic of extension, once occurred in the Cenozoic of the thrust and fold.The extension of Mesozoic bring up the fault basin sedimentary in Jurassic and cretaceous in the study area, sedimentary basin has obvious rapid accumulation characteristics, and thus formed the Jurassic and cretaceous basin sedimentary boundary of normal-strike slip fault. In profile, the hanging wall of faults is the Jurassic cretaceous stratum, the footwall of faults is the Proterozoic basement. In profile shows visible graben and horst combination features. Proterozoic basement rised gradually by the fault effect, it’s the evolution of initial prototype of Tuolai mountain and the South tuolai mountain.Under the influence of the India plate and Eurasian plate collision distance effect in Cenozoic, it occurred southeast to northwest extrusion shorten in study area, forming a series of thrust fault and fault-related folds,it shows imbricate structure.Main show is Proterozoic basement base of Tuolai mountain and South tuolai mountain as the center to the outer edge thrust of two sets of imbricated thrust fault type, with back thrust structural styles, and to accelerate the rise of mountains.Under the influence of the two geological events, experienced Mesozoic formed by normal fault effect slowly uplifted to the Cenozoic of rapid uplift of the structure of thrust back thrust type,Tuolai mountain and South tuolai mountain formed today’s mountain landscape. According to the previous research,there has been three uplift process about 89-31 M,31-8Ma,8Ma, the first activity time corresponding Mesozoic extension uplift, the second and third time for the Cenozoic of back thrust type role, the Oligocene to Miocene Baiyang river group of thrust can be corresponding to the second time, the Pleistocene series of Yumen group thrust can be corresponding to the third time. |
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